One of processes for dicing the substrate is known as a plasma dicing process which achieves a plasma-etching for the substrate with a mask thereon so as to divide it into a plurality of individual chips. Patent Document 1 (JP 2014-513868, A or U.S. Pat. No. 8,802,545 B2) discloses the plasma processing process for the substrate, in which the substrate is held on a conveying carrier that includes a frame and a holding sheet covering an aperture of the frame, and the substrate is set on a stage provided within a plasma processing apparatus, for ease of the handling of the substrate during delivery thereof.
The holding sheet is thin and easy to be bent so that the conveying carrier holding the substrate may be set on the stage with the holding sheet being crimped. When the plasma treatment is implemented with the holding sheet being crimped, the crimped portion may be exposed to an irregular discharge and/or intensive heat so that it may be difficult to achieve the plasma treatment in an appropriate or expected manner.
Many of electrical apparatuses have recently been smaller and thinner, and IC chips incorporated in such electrical apparatuses have also been thinner. Eventually, the substrate to be diced for producing the IC chips are also has been easier to be bent as well as the holding sheet. When such an easily warping substrate is adhered and held on the holding sheet, the crimps on the holding sheet tend to cause crimps on the substrate. Also, even slight distortion on the frame may more likely cause crimps on the holding sheet and the substrate.
The plasma treatment is carried out while the conveying carrier is set and contacted on the stage by an electrostatic chucking mechanism called as an electrostatic chuck. The electrostatic chucking mechanism pulls or sticks the holding sheet onto the stage by means of the coulomb force or Johnson-Rahbek force between the Electrostatic Chuck electrode (referred to as ESC electrode) provided within the stage and the holding sheet, upon application of voltage with the ESC electrode. In this situation, the holding sheet that holds the substrate may be pulled or stuck on the stage with the crimp thereon. The crimp on the holding sheet raises a portion of the holding sheet which should be pulled evenly onto the stage. This causes an insufficient contact between the substrate through the sheet and the stage.
The insufficient contact between the substrate through the sheet and the stage distorts the configuration of a plasma sheath generated at an interfacial surface between the substrate being plasma processed and a plasma atmosphere, so that the substrate may be etched unevenly, causing a variation of the processed shape and even non-processed portion of the substrate. Also, the insufficient contact may generate an intensive heat and/or an inappropriate discharge on a local point on the substrate. Such an intensive heat and/or an inappropriate discharge may damage the substrate, the holding sheet, and even the ESC electrode, which eventually cause a poor productivity.